Log debarking apparatus



Nov. 7, 1967 Q scHuRMAN LOG DEBARKING APPARATUS Filed July l2, 1965 ChjdeL. Schurmdn nited States Patet 3,351,109 LOG DEBARKING APPARATUS Clyde L. Schurman, Woodland, Wash., assignor to Schurman Machine Works, Inc., Woodland, Wash., a corporation of Washington Filed July 12, 1965, Ser. No. 471,203 5 Claims. (Cl. 144-208) ABSTRACT 0F THE DISCLOSURE A debarking machine comprising a pair of trunion wheel assemblies spaced one beside the other foi supporting a log, a carriage movable along a way substantially paralleling the axes of the trunnion wheel assemblies, a cutterhead mounting journaled on the carriage for downward swinging movement of its free end toward a log supported on the trunnion wheel assemblies, and a poweroperated cutterhead rotatably mounted on the mounting, such cutterhead having a generally cylindrically-shaped body, a pair of axially-spaced annular shoulders extending about the outside of such body and elongated ribs joined to the body distributed circumferentially thereabout with end portions curving radially inwardly on each end of the body and straight intermediate portions extending between said shoulders, such shoulders projecting radially outwardly on the cutterhead beyond the outer extremities of said ribs.

This invention relates to apparatus for removing bark and other peripheral growth from a log. A specific feature of the invention is the provision of a novel cutterhead for such apparatus, which facilitates the cutting away of knots and other irregularities in the outside of a log, and the removal of bark without the removal of valuable wood fiber from the outside of the log.

It is a common practice in the wood products industry, as the initial step in converting a log into other products, to remove the bark and cut off limb growth, knots and burls, etc. In such an operation, obviously it is an advantage that as little as possible of good wood growth be removed in the process. Further, any breaking down of the wood fibers about the periphery of the log, to cause fuzzing up on the outside of the log perferably is to be avoided. Additional requirements of a log barker are that the same be relatively easy to operate, and rapid in operation.

This invention contemplates a power-driven rotatable 'cutterheatL journaled on a mounting which is adapted to be swung to bring the cutterhead against the periphery of a log lying on suitable logesupporting mechanism. The mounting also is movable horizontally along a way, whereby the cutterhead may be progressively advanced along the length ofa log simultaneously with the removal of bark and other growth. The cutterhead features a novel construction whereby the same supports itself on the outside of a log in optimum relative position for the `clean and eicient removal of bark fromthe log. Thus,

the cutterhead includes spaced annular shoulders which provide t-he support, and scraper portions in regions adjacent each of the opposite ends ofthe cutterhead that break away the bark. Between these shoulders, and extending generally parallel to the axis of the cutterhead are elongated cutter portions used in the removal of knot growth, burls, etc. During bark removal the annular shoulders mentioned function to protect the cutter portions in the cutterhead from dulling.

A general object of the invention, therefore, is to provide improved apparatus for removing bark and peripher- "al growth from a log, featuring a unique type of cutterhead constructed to enable clean removal of bark without n l '3,351,1@9 Patented Nov. 7, 1967 removal of valuable wood ber and fuzzing up of the wood.

Another object is to provide a cutterhead constructed in such a manner that greater control is permitted in regulating the depth of cut produced by the cutterhead than previously possible.

More specifically, an object is to provide a cutterhead which includes a generally cylindrical body and multiple annular supporting shoulders spaced axially therealong functioning to maintain bark scraping portions in the cutterhead in proper position to perform their bark removal function.

Another object is to provide such a cutterhead, including multiple spaced supporting shoulders, wherein cutter portions are provided in a region located between axially spaced supporting shoulders, which cutter portions are protected by the shoulders during the removal of the bark. The cutter portions `are available for use in the removing of knots, burls and other protuberances in a log, and also may function to clean up the outside of a log after initial bark removal by the scraper portions in the cutterhead.

These and other objects and advantages of the invention will become more fully apparent from reading the following description, which is to be taken in conjunction with the accompanying drawings, wherein:

FIG. 1 is an elevation illustrating log barking apparatus embodying the invention, such apparatus including -mechanism for supporting a log in a substantially horizontal position, and a cutterhead disposed over this supporting mechanism adapted to be brought down against the log for the purpose of removing bark and other growth;

FIG. 2 is an enlarged side view of the cutterhead removed from the mounting; and

FIG. 3 is an end view of the cutterhead.

Referring now to the drawings and first of all more particularly to FIG. l, here log barking apparatus such as might be employed for removing bark and knot growth from the outside of a log is indicated generally at 8. The apparatus comprises a frame 10, log-supporting mechanism 12 for supporting a log while the same is having its bark removed, and a carriage 14 movable along way 15 in a path generally paralleling theA longitudinal axis of a log being barked. The carriage mounts a cutterhead mounting 19 and a cutterhead 17, to be more particularly described. A

Log-supporting mechanism 12 comprises what are referred to as a pair of trunnion wheel assemblies 16 and 18. Each comprises a trunnion shaft, such as shaft 20, journaled at opposite ends in bearings represented by bearing 22. Secured to each trunnion shaft at points distributed along the length thereof are a series of trunnion wheels, as illustrated by wheel 24. These wheels have teeth 26 about the peripheries thereof, provided to give greater traction wtih any log supported on the trunnion wheels.

Not shown but part of the apparatus is a suitable drive motor connected to the two trunnion shafts ofthe trunnion wheel assemblies. The driving connection between the motor and the shafts is such that on energizing of the motor, the two shafts are rotated in the same direction. A log to be processed, indicated by the outline 28, is cradled between the two trunnion wheel assemblies, between upper converging portions of the wheels in the assemblies. With rotation of the trunnion wheel shafts, a log so cradled is made to revolve about its longitudinal axis, in a direction opposite to the direction in which the trunnion wheel shafts are rotated.

Carriage 14 is supported on way =15 for movement to and fro along a horizontal path which generally parallels the trunnion wheel shafts and thus the longitudinal axis of the log supported on the assemblies. Suitable poweroperated means (not shown) is provided for shifting the carriage back and forth on the way.

Cutterhead mounting 19 is journaled at 34 on carriage 14. The mounting has an end 36 which is swingable up and down about the pivot axis provided by journal 34. The particular elevation of end 36 is determined by ram 40, including a cylinder 42 which is fastened to cutterhead mounting 19, and a rod 44 extending from the base of the cylinder which has its lower end suitably anchored to carriage 14. Thus, with contraction of the ram, the rear of the mounting is moved downwardly with upward swinging of end 36, and conversely, on extension of the ram the rear of the mounting is lifted to force the forward end of the cutterhead mounting downwardly toward the trunnion wheel assemblies.

Removal of bark and other material from a log is performed by cutterhead 17 which is journaled on end 36 of the cutterhead mounting. The cutterhead is rotated under power, ordinarily in a direction opposite to the direction in which a log is revolved by the trunnion wheel assemblies, by means of a motor 52 and suitable drive means (not shown) connecting such motor to the cutterhead encased in housing structure 53.

Considering now details of the cutterhead, and referring now also to FIGS. 2 and 3, the cutterhead comprises a generally cylindrical body portion 54 having tapered and thus generally rounded ends 54a, 54b. Projecting out from the extremities of these ends are shaft portions 56 employed in mounting the cutterhead in the cutterhead mounting.

As indicated above, an important part of the invention is the provision of novel means in the cutterhead facilitating proper positioning of the cutterhead relative to the log being processed. Such positioning means in the embodiment shown comprises a pair of rings 58, 60 integral with body portion 5t), forming annular shoulders extending about the outside of the cutterhead. One ring is adjacent but somewhat inwardly of each end of the cutterhead. The rings have substantially equal diameters, and each is concentric with the rotation axis of the cutterhead (such axis coinciding with the axes of shaft portions 56).

The cutterhead further comprises plural ribs 62, also integral with the body of the cutterhead. Each rib includes an intermediate portion, such as portion 62a, located between the annular rings 58, 60, which extends substantially parallel to the rotation axis of the cutterhead, and turned over end portions 62b, 62C, which curve around the tapered ends of the cutterhead body. All of the ribs are essentially the same. The ribs are equally circumferentially spaced about the outside of the cutterhead. It should be noted that intermediate portion 62a of a rib, together with end portions 62b, 62C, -all lie radially inwardly of the outer extremities of rings 58, 60.

Turned over end portions 62b, 62C of a rib function as scraping portions in the cutterhead. -It is these portions of a rib which initially move into a layer of bark, and strike the bark to break it up and dislodge it, In operation, the cutterhead is rotated in the direction of the arrow shown in FIG. 2. With such rotation of the cutterhead, edges 66, 68 of a set of turned over end portions are the edges that advance into the bark. Ordinarily no attempt is made to maintain these edges sharp, as they Iwould rapidly dull if sharpened. The removal of bark, therefore, is accomplished more by pounding and scraping the bark, with such then breaking away, rather than by any cutting action.

Intermediate portion 62a of a rib, however, has an edge 70 which leads the rib when the rib moves into a log, and this edge ordinarily is maintained quite sharp. These edges on the intermediate portions of the various ribs are utilized in removing protuberances such as knots and burls, and keeping these edges sharp is important in facilitating removal of this material as removal is the result of cutting or slicing the material away.

Explaining now the operation of the apparatus, ordinarily it is the practice for an operator, after placing a log on the trunnion wheel assemblies, to shift the carriage to appropriate areas and rst to even oif protuberances such as limb growth and knots. In this evening of the outside of a log it is the intermediate portions of the ribs that are utilized, as just discussed.

After removal of such material, the carriage is shifted to place the cutterhead adjacent but somewhat inwardly of one end of a log on the trunnion wheel assemblies. The cutterhead is then dropped down against the log, with suitable actuation of ram 40, and this results in the quick removal of a strip of bark extending about the log. To bark the extreme end of the log, the carriage is then moved axially of the log to shift the cutterhead to directly adjacent the extreme end of the log, and the turned over ends of the ribs during this movement advance into the bark and by striking it repeatedly cause it to be thrown off. During this barking of the log end, the outer surfaces of the rings ride on the freshly barked surface of the log, and perform the function of properly positioning the ends of the ribs. Because of the presence of multiple rings, a localized depression in the outside of the log does not result in a material change in the position of the cutterhead relative to the log. Further, the operator need not take special extreme care to see that one ring does not move off the end of the log (which, if only one ring was present, would cause the cutterhead to drop too close to the center of the log and cause tapering or pencil ending of the log).

After having removed the bark from one log end, the cutterhead may be advanced toward the opposite end of the log to bark the remainder of the log. During this portion of the barking operation, it is the turned over end portions of the ribs on the opposite end of the cutterhead that perform the bark removal. The rings lagain function to position the cutterhead properly on the logs periphery.

During substantially the entire barking operation, the intermediate portions of the ribs move past the log while lclearing the log, and in this way the cutting edges on these intermediate portion are maintained sharp. It has been noted that there is relatively little fuzzing up of the outside of the log by loosening wood liber thereon, probably explainable by the fact that the turned over end portions of the ribs extend for the most part in a radial direction. Further, where loose wood iiber is produced by the end portions, such is quickly cleared away by the intermediate portions of the ribs, which have sharp cutter edges and which follow the end portions of the ribs with the cutterhead advanced in a given direction along a log.

The presence of multiple spaced rings on the outside of the cutterhead has the further advantage of making less critical the exact amount of pressure used in forcing the cutterhead against a log. The two rings acting together minimize any tendency for the cutterhead to penetrate too far into the side of a log. Thus there is no need for an operator to be constantly vigilant and constantly changing cutterhead pressures with changes in type of bark, bark thickness, etc.

While an embodiment of the invention has been described, obviously variations and modifications are possible without departing therefrom. It is intended to cover all variations and organizations such as would be apparent to one skilled in the art, and that come within the scope of the appended claims.

It is claimed and desired to secure by Letters Patent:

1. A cutterhead for removing peripheral growth from a log comprising a body with means adjacent opposite extremities thereof for rotating the body about an axis extending through the body,

at least a pair of axially spaced annular shoulders concentric with said axis joined to said body and extending about the outside of said body, said annua log comprising a body with means adjacent opposite extremities thereof for rotating the body about an axis extending through the body,

elongated ribs joined to said body distributed circumferentially about the outside of said body, each of said ribs including end portions that curve radially inwardly on each end of the body, and substantially straight intermediate portions substantially paralleling the axis of said body, said intermediate portions of said ribs all lying at substantially equal distances from the axis of said body, and

at least a pair of annular shoulders joined to said body of substantially equal outer diameter, spaced axially on the body, with said intermediate portions of said ribs being located in a region bounded by said shoulders.

3. A cutterhead for removing peripheral growth from a log comprising a generally cylindrically shaped body with rounded ends,

elongated ribs joined to said body distributed circumferentially about the outside thereof, each of said ribs including end portions that cur-ve radially inwardly over the rounded ends of said body, and substantially straight intermediate portions substantially paralleling the axis of said body, said intermediate portions of said ribs all lying at substantially equal radial distances from the axis of said body, and

at least a pair of annular shoulders of substantially equal outer diameter and concentric with the axis of the body, joined to the body at axially spaced points thereon, with said intermediate portions of said ribs being located in a region bounded by said shoulders,

said shoulders having circumferential outer extremities spaced radially outwardly on. the body a greater distance than the outer extremities of said ribs.

4. A debarking machine comprising log-supporting mechanism for rotating a log while supporting the log in a generally horizontal position,

a cutterhead mounting adjacent said log-supporting mechanism,

power-operated means operatively connected to said mounting, operable when actuated to shift the mounting toward a log supported on said log-supporting means, and

a cutterhead rotatably mounted on said mounting for rotation about an axis substantially paralleling the longitudinal axis of a log supported on said logsupporting mechanism,

said cutterhead comprising a generally cylindrically shaped body,

a pair of axially spaced annular shoulders spaced axially on the cutterhead body and extending about the outside thereof, and generally axially extending cutter portions joined to the body in a region located intermediate said annular shoulders, said cutter portions having cutting edges spacedl radially inwardly on the cutterhead from the circumferential outer extremities of said annular shoulders.

5. The debarking machine of claim 4, wherein said cutterhead further comprises scraper portions distributed circumferentially about the cutterhead, in regions which are toward the ends of the cutterhead from the region Where said cutter portions are located, and such scraper elements are bounded by outer scraping surfaces disposed radially inwardly of the circumferential outer extremities of said annular shoulders.

References Cited UNITED STATES PATENTS 1,255,494 2/ 1918 Witham. 2,401,500 6/ 1946 Ockfen. 3,082,801 3/196-3 Dillingham.

WILLIAM W. DYER, JR., Primary Examiner. W. D. BRAY, Assistant Examiner. 

1. A CUTTERHEAD FOR REMOVING PERIPHERAL GROWTH FROM A LOG COMPRISING A BODY WITH MEANS ADJACENT OPPOSITE EXTREMITIES THEREOF FOR ROTATING THE BODY ABOUT AN AXIS EXTENDING THROUGH THE BODY, AT LEAST A PAIR OF AXIALLY SPACED ANNULAR SHOULDERS CONCENTRIC WITH SAID AXIS JOINED TO SAID BODY AND EXTENDING ABOUT THE OUTSIDE OF SAID BODY, SAID ANNULAR SHOULDERS HAVING SUBSTANTIALLY EQUAL OUTER DIAMETERS, ELONGATED CUTTER PORTIONS JOINED TO SAID BODY, SUBSTANTIALLY PARALLELING THE AXIS OF SAID BODY AND CIRCUMFERENTIALLY DISTRUBUTED ABOUT THE OUTSIDE OF SAID BODY, IN A REGION LOCATED BETWEEN SAID ANNULAR SHOULDERS, SAID CUTTER PORTIONS HAVING AXIALLY EXTENDING CUTTING EDGES ON RADIALLY OUTER PORTIONS THEREOF LOCATED ON THE CUTTERHEAD RADIALLY INWARDLY OF RADIALLY OUTER EXTREMITIES OF SAID SHOULDERS. 